pg_last_oid() is used to retrieve the oid assigned to an inserted tuple (record) if the result resource is used from the last command sent via pg_query() and was an SQL INSERT. Returns a positive integer if there was a valid oid. It returns FALSE if an error occurs or the last command sent via pg_query() was not an INSERT or INSERT is failed.
OID field became an optional field from PostgreSQL 7.2. When OID field is not defined in a table, programmer must use pg_result_status() to check if record is is inserted successfully or not.
Замечание: This function used to be called pg_getlastoid().